Carrie Fisher's death certificate confirms heart attack

Carrie Fisher’s death certificate confirms that the actress died of a heart attack, but it says more investigation is needed to try to determine the underlying cause, CBS reports.

The Los Angeles County Department of Public Health issued the death certificate in the name of Carrie Frances Fisher. It was obtained Monday by The

Under “cause of death” it says “cardiac arrest/deferred.” The “deferred” designation indicates that more investigation is needed by the county coroner, usually in the form of toxicology tests that can take several weeks to complete.

Fisher’s daughter Billie Lourd is listed as the notifying party.

Fisher had the heart attack on a flight from London to Los Angeles on Dec. 23. She died at age 60 on Dec. 27 at Ronald Reagan UCLA Medical Center, the certificate says.